When I click on my larger categories, I now get an error that says:
"You select too much criteria for query! Cannot display results."
If I attempt to do a search on one of those categories, the program crashes.
That's the whole reason I got picajet! I want to query one category based on another. If you can't do this, what's the point! If it comes down to the number of pictures in each category, I can guarantee they are only going to get bigger over time.

Can't you get rid of the limitations? I understand that a query of this size may take longer, but I have a necessary query and a necessary category structure. The main purpose of my database is to organize my plant pictures. Each plant has to have its own name, each of those needs to be under their family, and they all need to be under a basic plant category. This gives the basic structure of plant_category/family/scientific_name. In the future there will likely be as many as 10,000 child categories, maybe more. I also have a separate category structure for the locations the photos were taken. How can I find out which plant photos were taken in a certain area if I can't query the main plant category? It seems that, as far as database queries go, it can't get much simpler than that.